1. Field of the Invention
The present invention relates to a drive unit for use with an adjustable width drive axle.
2. Description of Related Art
A crop sprayer is a machine that includes a storage tank for storing chemical such as herbicides, pesticides, and fertilizers that are to be sprayed onto crops that are growing in a farm field. The chemical within the storage tank is sprayed onto the crops growing in the field by use of a nozzle assembly secured to a number of booms as the crop sprayer is advanced along the rows of the field.
Preferably, the crop sprayer should be able to operate in a number of varying field conditions. For example, the distance between rows of plants varies from field to field. Accordingly, it is desirable to provide a crop sprayer that is capable of adjusting the distance between its two right wheels and its two left wheels to allow the crop sprayer to move down the rows associated with the field without damaging or destroying the crops. In order to accommodate this need, crop sprayers have been designed with adjustable-width axle assemblies. However, the current designs of adjustable-width axle assemblies have a number of drawbacks. For example, adjustable-width axle assemblies are relatively mechanically complex and include a relatively large number of components thereby increasing the costs associated with manufacture and operation of the crop sprayer. Moreover, certain adjustable-width axle assemblies are susceptible to mechanical failure thereby reducing the useful life of a number of the components associated with the crop sprayer.
It should be appreciated that the crop sprayer must also be configured to easily and efficiently traverse varying surface topography when being operated in the field. For example, due to the long boom arms which crop sprayers require in order to cover many rows of crops with a single pass, a small change in the angle at which the chassis of the crop sprayer is oriented results in a large height change at the end of the boom arm thereby reducing crop clearance of the lowered boom arm. Crop damage may occur if the boom arms sway back and forth across a relatively large distance as the crop sprayer encounters varying surface topography or if the boom arms are significantly moved upwardly and downwardly as the crop sprayer executes a turn. Moreover, the environment in which the crop sprayer is operated, a farm field, is particularly prone to having varying surface topography.
What is needed therefore is an adjustable width axle drive and drive unit that overcomes one or more of the above-mentioned drawbacks. What is further needed is an adjustable-width axle assembly that can be quickly and easily utilized to change the operational width of the drive axle.